Process for producing a therapeutic composition

ABSTRACT

A stabilized, therapeutic composition is provided which comprises an aqueous medium containing known amounts of Na , K , HCO3 , and Cl wherein the pH of the solution is maintained between about 6 and 8.5 and the osmolality is maintained between about 170 and 460 by maintaining a gaseous mixture as a blanket over the solution during manufacture and storage, the gaseous mixture containing a sufficient amount of carbon dioxide to substantially equal the partial pressure of the carbon dioxide produced from equilibrium within the solution.

United States Patent Zinke Apr. 22, 1975 1 1 PROCESS FOR PRODUCING A 3.406.079 10/1968 Gibble 53/22 R x THERAPEUTIC COMPOSITION 3.676.553 7/1972 Reynolds 424/!28 3.705.100 12/1972 Blatt 210/23 [75] Inventor: Charles D. Zinke. Fort Worth. Tex.

[73] Assignee: Cybersol Inc.. Dallas. Tex.

[22] Filed: Nov. 27, 1972 [21] App1.No.:308,02l

[52] US. Cl. 53/22 R; 53/25 [51] Int. Cl B6511 31/02 [58] Field of Search 53/22 R. 112 R. 424/128. 424/153: 210/23 [56] Reierences Cited UNITED STATES PATENTS 1.356.511) 12/1967 Barnhy 53/2 R X Primary Examiner-Travis S. McGehee Assismn! Examiner.lohn Sipos Attorney, Agent. or Firm-Richards. Harris & Medlock [57] ABSTRACT A stabilized. therapeutic composition is provided which comprises an aqueous medium containing known amounts of Na". K. HCO and Cl wherein the pH of the solution is maintained between about 6 and 8.5 and the osmolality is maintained between about 170 and 460 by maintaining a gaseous mixture as a blanket over the solution during manufacture and storage. the gaseous mixture containing a sufficient amount of carbon dioxide to substantially equal the partial pressure of the carbon dioxide produced from equilibrium within the solution.

14 Claims. 1 Drawing Figure 2 H20 Soluble Solis CO2 N2 Nc+- K+ Q) HCO- Mqt?

l 2 3 4 STERILIZATION SALT ADDITION PROTECTIVE MlXlNG BLANKET 5 FILTER CO -N I 9 IO FIEFLUSH DISPENSlK: PROTECTIVE SEALING BLANKET PROCESS FOR PRODUCING A THERAPEUTIC COMPOSITION This invention relates to therapeutic compositions. In another aspect. this invention relates to a novel method of making a therapeutic composition. In still another aspect. this invention relates to a novel method of con trolling the pH and osmolality of a therapeutic solution containing bicarbonate ions. In still another aspect. this invention relates to a novel means of containing a therapeutic solution of bicarbonate ion which will maintain the therapeutic solution at a constant pH and osmolality.

After accidental or elective operative injury to human patients. there occurs a decrease in the hemoglobin concentration. an elevation in the erythrocyte sedimentation rate of peripheral blood. and a loss of red blood cells from the effective blood volume. These events are recognized as anemia. Also. immediately subsequent to the injury. the white cell count is usually elevated. and the thrombocyte count is decreased. implicating pancytic mechanisms.

The administration of whole blood is useful to rectify the pancytic changes. However. most surgeons have been unable to maintain adequate quantities of peripheral total hemoglobin. red blood cells. and thrombocytes through the use of whole blood. even when quantities far in excess of that lost by bleeding are infused. Furthermore. it is known that the collection and storage of whole blood generally produces a hyperosmolar.

acidic water solution as the result of changes in the red blood cells and blood water during collection and storage. Other disadvantages in the use of whole blood include its expense. and it may produce unwanted immunohematological responses in the recipient.

The surgeon and anesthesiologist have traditionally had four other choices instead of whole blood infusion to correct the above-described adversities. The four other choices include the administration of( l plasma. (2) separated (packed) erythrocytes. (3) synthetic water solutions. or (4) synthetic water solutions containing synthetic protein. Plasma has some of the disadvantages of whole blood. Separated erythrocytes. besides being expensive. have the disadvantage of decreases in functional and structural life after reinfusion.

ln recent years. synthetic water solutions with or without protein have been utilized to maintain the cir' culating blood volume and for maintenance of blood pressure. This is accomplished by replacing or attempting to replace that extracellular water which is lost to urine formation, in the wound. in respired air. and through the skin. and furthermore. by providing an amount sufficient to compensate for the enhancement in blood volume capacitance secondary to anesthetic agents. The first synthetic water solutions developed in the prior art emphasized ionic content. particularly sodium chloride. with little regard to other physiochemical requirements. However. the use of such materials did not achieve efiective blood volume and extracellular water maintenance without excessive water administration and water retention. These excesses contribute to many vexations which extend the patient recovery time. Such vexations include gastro-intestinal water retention with hyptonia. ventilatory and other pulmonary problems, aberrations in urine volumes. muscular weaknesses. and sometimes cerebral disorientation.

Some of these conventionally utilized water solutions include sterile. U.S.P. water for injection. normal saline solutions. dextrose (5 percent) in saline or water. and solutions containing so-called bicarbonate precursors such as Lactated Ringers. The latter types of solutions contain materials which are said to be bicarbonate precursors in that they are designed to release sodium ions after they have been infused into the bloodstream.

Recently. an improved synthetic water solution has been developed which overcomes many of the deficiencies of the prior art solutions. and its use reduces the above-described vexations which extend the patient recovery time. This improved therapeutic solution is disclosed in US. Pat. No. 3.676.553. and depends for its effectiveness upon the maintenance of proper osmolal pressure. proper pH. and proper ionic content. Since osmolal pressure and pH of a synthetic water solution injected into the bloodstream are dependent upon the total number of active soluble particles moving with varying speeds in the solution. the selection of solutes for the above-described novel synthetic water solutions was accomplished by utilizing the most rapidly moving hydrated solutes with optimal activity coefficients. but yet which are compatible with physiological waters of extracellular water and intracellular water. This new therapeutic composition utilizes sodium as its primary cation since sodium is recognized widely as the cation with primary activity in the extracellular water. The novel composition utilizes chloride as the principal anion. since chloride is the principal anion in extracellular water. The chloride enhances retention of intracellular potassium. the leading cation of the intracellular water. Furthermore. the above-described therapeutic composition contains potassium in quantities preferably equal to its mean concentration in extracellular water including the water of the circulating red cell mass. Free bicarbonate ion is utilized in this new therapeutic composition because free bicarbonate is an essential solute in both extracellular water and intracellular water and causes potassium to shift into the cells. The novel therapetuic composition can contain other ions such as magnesium (Mg"*) and/or ((Ta) as the principal minor solute cation and phosphate (HPOfl and/or sulfate (50.) as the principal minor solution anion.

Thus. the bicarbonate ion which is present in the above-described novel therapeutic composition is not the conventional bicarbonate precursor such as sodium lactate. but is true bicarbonate ion. Evidence shows that in vitro ionization of sodium lactate which is utilized in synthetic water solutions such as Lactated Ringers rarely exceeds about percent. Furthermore. in order to accomplish the physiochemical purposes of causing potassium to shift into cells. the bicarbonate which is present in the synthetic water solutions must be in the form of bicarbonate ion and not in the form of the conventional precursors therefor. Thus. the physiochemical and physiological requisites for bicarbonate in the solution are satisfied by true bicarbonate solute alone. As set forth in the above-identified patent. when the novel therapeutic composition is utilized par enterally in conjunction with accidental or elective operative injury. the concentration of the abovedescribed solutes are adjusted so that the solution has an osmolality of about 300 milliosmoles per liter (mOsm/L) and a pH of from about 7 to 7.6. preferably about 7.2. Furthermore. the osmolality and the pH of the above-described novel solution can be adjusted for other uses. For example. solutions having an osmolality of less than about 290 can be designed to move into the cells; thus. such solutions are usable in treatment of heat stroke or situations causing excessive sweating. Furthermore. solutions ha\ing an osmolality in excess of about 3 can be designed to attract water out ofthe cells. As a result. such solutions are usefui. for example. in the treatment of overdoses of barhituates or any situ ation resulting in the unusual accumulation of water within the cells.

In general. the above-described improved therapeutic composition comprises an aqueous medium containing from about 75 to I50 millimoles of Na. about 5 to 50 millimoles of K. about 5 -50 millimoles of HCOJ. about 75-150 millimoles of Cl 1 and preferably contains about millimoles of Mg and/or Ca and about l-30 millimoles ofHPO. and/or SOf' The solution can have a varied pH and an osmolality in the range of from about l70 to 460. depending on its use.

Great care must be taken when manufacturing this novel composition, especially in veiw of the fact that it is relatively difficult to maintain desired concentration of true bicarbonate ion in solution due to its sensitivity to environmental changes. More specifically. the bicarbonate ion in solution is in constant equilibrium with water and CO and slight changes of temperature and pressure during manufacture and storage of the solution can result in an undesirable shift in the equilibrium and a loss ofthe true bicarbonate ion from the solution.

Accordingly. one object of this invention is to pro vide a novel process for making an aqueous therapeutic composition containing true bicarbonate ion.

Another object of this invention is to provide a novel process for stabilizing an aqueous therapeutic composition containing true bicarbonate solute.

A further object ofthis invention is to provide a novel container means for enclosing an aqueous therapeutic solution containing a regulated amount of bicarbonate ion.

According to one embodiment of this invention, a method of controlling the osmolality and the pH of an aqueous therapeutic composition containing a known quantity of bicarbonate ion is provided by maintaining a gaseous blanket over the said solution. said gaseous blanket containing carbon dioxide in a sufficient amount to prevent the loss of bicarbonate ion from solution. The gaseous blanket preferably contains carbon dioxide and at least one other inert gas. the carbon di oxide being present in a sufficient amount to substantially equal the partial pressure of the carbon dioxide produced from equilibrium within said solution at the temperature of said solution.

More specifically. one embodiment of this invention comprises a method of maintaining the pH of a therapeutic composition within the range of from about 6 to about 8.5. which composition comprises an aqueous medium containing about 75-l50 millimoles of Na". about 5-50 millimoles of K*. about 550 millimoles of HCO about 75-150 millimoles of Cl. up to about 30 millimoles of Mg. and/or Ca and up to about 30 millimoles of HPOF. and/or 50 and having an osmolality in the range of from about l70460. by maintaining a gaseous blanket over the solution which comprises a mixture of carbon dioxide and another inert gas or gases. the carbon dioxide being present in the gaseous mixture in an amount to maintain a pH in the solu' tion in the range of from about 6 to about 8.5 at a temperature in the range of from about 25 to about 50C.

According to another embodiment of this invention. a novel method is provided for manufacturing an aque' ous therapeutic composition containing a predetermined amount of bicarbonate ion solute which includes initially providing a sterile water volume and thereafter dissolving water soluble salts containing ions which include bicarbonate in the solution. and next. blanketing the resulting solution with a mixture of carbon dioxide and inert gas. such as nitrogen. wherein the carbon dioxide is present in the gaseous mixture in an amount to provide a partial pressure on the liquid which is substantially equal to the partial pressure which is produced from equilibrium in the solution at the solution temperature and thereafter, agitating the solution to assure complete dissolution of all the water-soluble salts therein. The stabilized solution is then dispensed within pyrogen-free containers which have been preflushed with the above-described gaseous mixture. and then covered with the above-described gaseous mixture. and sealed. The stabilized solution while blanketetl by the above-described gaseous mixture can be sterilized by conventional techniques. In accordance with a preferred embodiment of this invention. the solution is filtered by passing it through membrane filters containing pores generally less than 1 micron in diameter before it is dispensed within the pyrogen-free containers.

According to another embodiment of this invention. a novel shipping and dispensing container means is provided for an aqueous therapeutic composition containing bicarbonate ions which comprises a container hav ing the solution as a liquid phase and the abovedescribed gaseous mixture as a protective blanket gase ous phase sealed therewithin.

The therapeutic composition made in the scope of this invention can be administered orally but preferably parenterally. The therapeutic composition made in accordance with this invention is preferably equi-osmolar with respect to the mean osmolality of extracellular water (ECW) and is designed to minimize water movements into fixed cells after operative. anesthetic and accidental trauma. In addition. the preferred parenteral solution diminishes loss of functional decrements in all body systems, particularly heart and circulating fluids. lung. kidney. gastro-intestinal tract and brain.

The therapeutic composition made in accordance with this invention contains sodium (Na") and potassium (K) as the pincipal major cation solutes. and true bicarbonate (HCOJ) and chloride (Cl) as the primary anion solutes. In addition. other solutes such as magnesium (Mg and/or calcium (Ca*"). phosphate HPOf) and/0r sulfate (50F) and IOA {impermeable organic anions) can be present in the therapeutic composition all in accordance with the teachings of US. Pat. No. 3,676,553. which is hereby incorporated by reference into this specification. In addition. the therapeutic solution made in accordance with this invention can have an osmolality Within the range of from about to about 460. preferably from about 260 to about 340. more preferably from 290 to 3 l0. and most preferably about 300. It is noted that osmolality as used in the scope of this invention means the specific number of millimoles dissolved in l liter of water. The osmolal ity can be directly measured with a conventional osmometer such as manufactured by Advanced lnstruments lnc. of Newton Highlands. Massachusetts. Generally. the solutions made in accordance with this im vention have a measured osmolality in the range of from about 170 to about 460 at 37C. The osmometer is basically a freezing point depression apparatus which utilizes a standard reference solution. Standard aqueous solutions of NaCl can be made up in a conventional manner. For example. a standard theoretical 300 milliosmole NaCl solution consists of l50 millimoles per liter of NaCl. Another standard which can be used to measure the osmolality is normal human blood plasma which has an osmolality of 298 milliosmoles per liter at 37C.

In addition, the pH of the therapeutic solution made in accordance with this invention can range from about 6.0 to about 8.5 and is preferably within the range of from 7.0 to 8.0. and more preferably in the range of from 7.0 to 7.6.

The therapeutic composition manufactured and packaged in accordance with this invention can contain varying amounts of the principal and minor cation and anion solutes. and thus a wide range of osmolaiity and pH. but yet be stable at such concentrations. Generally. the concentration of the ions in the therapeutic composition made in accordance with the subject invention can be as set forth in Table I below:

This invention can be more easily understood from a study of the drawing which comprises a schematic diagram depicting a preferred procedure for manufacturing the therapeutic composition in the scope of this invention.

Now referring to the drawing. a typical batch type reaction process for producing a therapeutic composition of the scope of this invention is schematically illustrated. It is noted that the process of the subject invention can be practiced as a continuous process if desired; however, it will be described in detail in terms of a batch process.

Now referring to the drawing in detail. initially a predetermined volume of U.S.P. water is obtained. Preferably. distilled water is added to a pressure-scalable batch reactor and sterilized to remove pyrogen contaminants therefrom. A suitable sterilization cycle includes heating the distilled water to a temperature of 12 lC for a period of at least an hour. Any other heating cycle can be utilized which is suitable for removing pyrogen contaminants from the water. A suitable batch reactor comprises a pressure scalable reactor equipped with an internal stirring mechanism and suitable means to heat the interior thereof such as a steam jacket.

After the sterilization step. the resulting pyrogen free water is cooled to a temperature within the range of from about 25 to about 50C and more preferably within the range of from about 25 to about 40C.

After the water has been cooled. predetermined amounts of salts can be added to the interior of the reactor to produce a solution of a desired osmolality. Known water soluble salts containing the ions which are desired for the therapeutic composition can be utilized. Examples of such salts include NaCl. KCI. NaH- CO KHCO MgCl CaCl M1 50 NHQHPO. MgSO and K- HPO,. In addition. if desired. a chelating agent such as disodium edetate [disodium (ethylene dinitrilo) tetraacetatel can be added at this point. The chelating agent will serve to sequester any trace amounts of metal ions such as tin. zinc and aluminum ions and prevent the hydroxide formation and precipitation thereof. Typical solutions produced in accordance with this invention are made by the addition of sodium chloride. potassium chloride. magnesium sulfate. disodium edetate. and sodium bicarbonate to the sterile water. It is noted that it is preferably to add the sodium bicarbonate to the water after the other salts have been dissolved therein. ln essence. it is preferable to add the so dium bicarbonate to the solution which contains the other dissolved salts so that the water has multiple ions in solution. This addition sequence has the effect of preventing any unwanted reaction between the magnesium salts. such as magnesium chloride and bicarbonate ions which may form a resulting precipitate of the magnesium carbonate. for example.

After the salt addition to the water. the solution is then blanketed (step 3 in the drawing) with a carbon dioxide-inert gas atmosphere, preferably at one atmosphere pressure. And then thoroughly agitated (step 4 in the drawing) to assure complete dissolution of all of the salts in the sterile water.

The gaseous protective blanket contains sufficient carbon dioxide to prevent loss of carbon dioxide from the solution which is normally produced from equilibrium conditions of the bicarbonate in solution. In essence, the carbon dioxide is present in the gaseous mixture in an amount to provide a partial pressure on the liquid which is substantially equal to the partial pressure which is produced from equilibrium of bicarbonate in the solution at the mixing temperature.

More specifically, the carbon dioxide is present in the gaseous blanket in an amount to maintain a pH of the solution in the range of from about 6 to about 8.5 at a temperature in the range of from about 25 to about 50C (the temperature of the solution). As set forth above. the therapeutic solution of the subject invention can contain bicarbonate ion in the range of from about 5 to about 50 millimoles per liter. Accordingly. from about 0.0007 to about 0.92 atmospheres of carbon di oxide are necessary to maintain a pH of the solution within a pH in the range of from about 6 to about 8.5. The amount of carbon dioxide in the gaseous blanket can be derived by simple physical chemical calculations.

The remaining gaseous component in the gaseous protective blanket can comprise any inert gas which is non-deleterious to the solution. By nondeleterious to the solution" it is meant that the gas should not react with the solution and it should not change the osmolality nor the pH of the solution when contacted therewith in any amounts.

Suitable gases include nitrogen. argon. helium. and the like. Because of its pharmaceutical acceptability 7 8 and availability nitrogen is generally preferred as the TABLE [1] component to be utilized in admixture with carbon dioxide in the protective gaseous blanket.

Furthermore. when used in the scope of this invenp k" tion to define the relative amount of carbon dioxide in which is present in the gaseous blanket the term par- PH Mum (1C0: ll i tial pressure which 18 substantially equal to the partial pressure which is produced from equilibrium in the 2 8363 therapeutic solution" is understood to mean the partial 0:: 01002101 0574 pressure of carbon dioxide which is ultimately desired after the solution has been formed and the gaseous caris 00 5 4 :170 bon dloxide blanket applied thereto. 116 52 5 0.152 In essence. the partial pressure of the carbon dioxide in the blanket can be adjusted to either stabilize the ini- 0.9 0.00295 0.0887 tial pH of the solution. or to actually contribute to the 3 final pH of the solution. For example. in the latter situa- 7:: 0.00161 00:11-14 tion. a solution can be initially formed to have a higher pH than that which is ultimately desired and the carbon b 4 1,5 1; dioxide in the gaseous blanket can be present in such 11.0204 .111. 0.0103 amounts toactually function in part to yield a lower pl-l N 0000433 mm" that that mitrally formed. In either case. the carbon (11- 7.0 0.000345 00104 oxide in the gaseous blanket serves to stabilize the normal equilibrium breakdown of the bicarbonate in solu 1112 0000174 0100520 i a the i desired pH- 11.3 0.000140 000420 A I I l f H A f b a 1 1.4 0.000111 0.00334 s an cxamp eo various amounts 0 car on oxide -5 85 0.00m, which can be utilized in the protective blanket in the scope of this invention with a preferred solution containing an osmolality of about 300 such as set forth belovt in Table II. the data in Table 111 are provided.

TABLE I1 As stated. the relative amount of carbon dioxide in Therapeutic Solution Having An osmulum), of the protective gas blanket can be determined by simple CONCENTRAHON physical chemical calculations. However. as a general Millimules P lite-fl guide. Table 1V is presented to illustrate preferred varim ous amounts of carbon dioxide in the gaseous blanket x 14 which can be utilized with from 5 to 50 millimoles of 28 i bicarbonate at pHs from 6 to 8.5 and at a temperature (1 3 in the range of from about 25 to about 50C for the 1 5 compositions made in the scope of this invention.

TABLE IV CO2 NEEDED TO STABlLlZE SOLUTION PART 1 Moles pH 6.0 pH 6.5 pH 7.0 pH 7.2 Bicarbonate Moles Pressure Moles Pressure Moles Pressure Moles Pressure Added to (Atm) (Atm) (Atm) (Atrn) Solution PART 2 Moles pH 7.6 pH 8.0 pH 8.5 Bicarbonate Moles Pressure Moles Pressure Moles Pressure Added to (Atm) (Atm) (Atrn) Solution Thus. as can be seen. therapeutic solutions of various osmolalities and pHs can be admixed in accordance with this invention under protective blankets containing corresponding amounts of CO;- which are substantially equal to the partial pressure which would be produced from equilibrium of the bicarbonate in each of the solutions at a temperature of from to 50C.

Now again referring to the drawing. the solution is agitated sufficiently to assure the dissolution of the salts for a period sufficient to assure the formation of the solution in the scope of this invention. It is noted that the agitation inherently exposes much of the surface of the liquid to the atmosphere within the vessel and would normally hasten the unwanted breakdown of the bicarbonate in the solution. However. the protective blanket of CO -inert gas utilized as the atmosphere within the agitated vessel will stabilize the equilibrium breakdown of bicarbonate in the solution.

It is noted that in some instances wherein a chelating agent such as disodium edetate is not added to the solution. and it is desired to rid the solution of any trace amounts of undesirable metal ions such as tin. zinc and aluminum. the solution should be heated or maintained at a temperature of about 40C after it is mixed in step 4 to cause the unwanted metal hydroxides to precipi tate therefrom. The precipitate will be removed by the filter step set forth schematically as step 5 in the drawing.

After the agitation step. it is preferable to check the pH of the agitated solution. Minor pH adjustments can be made at this time with known acids or bases. e.g.. HCl. NaOH. ctc.. whose reactions with the solution will not produce ion solutes different from the abovedescribed solutes which can be present in the solution.

After the solution has been formed by the admixing step. it is filtered to remove any bacteria. fungi. and other particulate contaminants therefrom. The solution is passed through a filter containing pores which are generally less than I micron in diameter. It is noted that bacteria have a size of between I and 2 microns and the filtration step should remove any bacteria. if present. from the solution. The solution can be passed through l or more filter membranes in series if desired. Generally. a suitable filtering system includes a pair of membrane filters in series. Suitable membrane filters include the ceramic membrane filters manufactured by The Millipore Corporation. Bedford. Mass. These membranes have a 0.22 micron porosity.

The filtered solution is then passed into a suitable holding tank (shown as step 6 in the drawing). Again. it is generally preferable to maintain the carbon dioxide-inert gas blanket over the filtered solution within the holding tank. It is noted that the solution which has been filtered and bacteria. fungi. and other particulate matter removed therefrom still can be unstable when placed in contact with the atmosphere. For example. if one were to place a beaker of the 300 osmolality solution which is set forth in Table ll above in contact with the atmosphere at room temperature. it would change approximately one-half pH point per hour. In addition. as the pH changes and carbon dioxide is lost from the solution into the atmosphere. the resulting osmolality of the solution will change correspondingly in a deleterious manner. The protective CO- -inert gas blanket which is used in the scope of this invention during the processing and storage steps will prevent such deleterious change in pH and osmolality of the therapeutic composition.

The stable sterile therapeutic composition which has been formed and retained in holding tank (illustrated as step 6 in the drawing) can be dispensed in any suit able container known in the art. The containers can be of a suitable volume. for example. conventional 500 or I000 milliliter infusion bottles. The containers can comprise glass containers or therapeutically acceptable plastic containers of various sizes and shapes including flexible bag-type containers made of polyvinyl materials. such as polyvinyl acetate having integral outlet tubing attached thereto.

Thus. any pharmacologically acceptable container known in the art can be utilized to bottle the therapeu tic solution made in the scope of this invention. All such containers are air tight and capable of receiving a liquid and gaseous material under one atmosphere pressure. in addition. the container materials should obviously not react with the therapeutic composition. When bottling the therapeutic compositions made within the scope of this invention which has a pH of 7 or higher. and when utilizing glass bottles for containers. it is preferred to use a glass material which will not react with the alkaline solution. Suitable glass materials include the borosilicate type glass bottles.

When filling the container with the stabilized therapeutic solution manufactured in accordance with this invention. it is preferred to initially preflush the sterile container with the same carbon dioxide-nitrogen mixture which is utilized in manufacturing the solution such as set forth schematically in step 7 of the drawing. The preflushed bottle is then passed to a filling stage wherein the stabilized therapeutic composition is dispensed therewithin. such as set forth schematically in step 8 of the drawing. After the stabilized therapeutic solution has been dispensed into the bottle. the bottle is then passed to another stage wherein the CO -N gas blanket is again passed over the liquid level within the container as shown schematically in step 9 of the drawing. After the Co -N gas blanket is formed over the liquid level in the container. the container is instantaneously sealed as set forth schematically in step l0 of the drawing. When utilizing a typical 500 milliliter glass infusion bottle. the bottle is capped with a solid black rubber stopper having an epoxy coating on the lower portion thereof adjacent the gas blanket. Any conventional lid is placed over the glass and stopper. such as an aluminum tamper-proof seal which is well known in the art. Basically. an aluminum disc is placed over the top of the stopper and then an aluminum cap is placed over the aluminum disc. Any other suitable conventionally available stopper means can be utilized.

As set forth above. any other suitable container means can be utilized. such as a flexible bag having integrally connected dispensing tubing for administering parenteral solutions. It is only necessary in the scope of this invention that the gaseous atmosphere inside the container comprise the Co -inert gas mixture which is utilized in manufacturing the solution as set forth above. The resulting article comprises a sealed container having a liquid phase comprising the therapeutic composition containing a known amount of bicarbonate ion and a gaseous phase comprising carbon dioxide inert gas and containing sufficient carbon dioxide to maintain the pH of the solution in the range of from about 6 to about 8.5 as desired. and a temperature range of from about 25 to 50C. The resulting bottle can be subjected to temperature extremes (above and below the above-stated range) to which pharmacological infusion materials may be normally subjected during shipment and storage. These temperature extremes will not affect the resulting composition. It is only desirable that before the solution is utilized that it be equilibrated at a temperature in the range of from to C and preferably about 254()C. The resulting liquid therapeutic composition can be parenterally administered to the patient and the physician will be assured that the solution contains true bicarbonate ions and will enter the patient at a known pH and osmolaL ity.

The above-described preferred embodiment for pro ducing the therapeutic composition of the subject invention which includes the filtration step comprises a process which achieves the highest level of pharmaceutical elegance. However. it is to be noted that other sterilization techniques can be used in the scope of this imention. In essence, any U.S.P. accepted sterilization standard can be utilized to sterilize the stabilized composition produced in the scope of this invention (the therapeutic composition stabilized by the described gaseous blanket). Such procedures which conform to U.S.P. standards are well known and include sterilization of containers with ethylene oxide gas prior to filling irradiation and autocalving. Such procedures can be utilized alone or in conjunction with the filtration step. For example, when autoclaving is used either alone or in conjunction with the above-described preferred filtration step, the stabilized therapeutic composition ha\ ing the abovedescribed gaseous blanket positioned thereover can be autoclaved, for example, in the infusion bottles after it has been dispensed therewithin. A suitable autoclave cycle will include heating the material to l2 1C for 24 minutes. for example. Thus, it is not absolutely necessary to utilize the filtration step to sterilize the stabilized therapeutic composition in accordance with the broad aspect ofthis invention. How ever, the filtration step is included in the preferred pro cess carried out in the scope of this invention.

The following examples are given to better facilitate the understanding of this invention and are not intended to limit the scope thereof.

EXAMPLE I 7,500 SUD-milliliter infusion bottles (with a 2 percent overfilll of an injectible therapeutic composition having an osmolality of 300 and a pH of 7.2 were manufactured in accordance with this invention by initially charging 3. 53]. [17 grams of U.S.P. water (water for injection) into a L000 gallon compounding tank. The L000 gallon compounding tank was equipped with an internal stirrer, a scalable cover with a bleeder valve, a bottom drain, and a heating jacket operated by steam. After the water was added to the compounding tank, the stirrer was activated. Next, the compounding tank was heated by the steam jacket to a temperature of C with the hatch open. After the water had reached 85C, the hatch cover was closed and sealed but the bleeder valve remained open. The water was heated further until it reached a temperature of between and 98C and thereafter the bleeder valve was closed. After the bleeder valve was closed, the water was heated to 121C for I hour.

Next, the contents of the tank were cooled to a temperature of between 25 and 30C and vented. After the solution had cooled the following materials were added to the sterilized water: 23,5 76 grams of sodium chloride; 3,727 grams of potassium chloride; 4,398 grams of magnesium sulfate heptahydrate; and 1,785 grams of disodium edetate. Next, the stirring mechanism was turned off and with the solution quiescent. 5.397 grams of sodium bicarbonate was added thereto. After the sodium bicarbonate was added to the solution. the solution was covered with a gaseous blanket which consisted of about 0.05 atmospheres of CO and 0.95 atmospheres of nitrogen and the compounding tank was sealed. Thus, the ratio of carbon dioxide to nitrogen was in the range of from I to 1:20. The batch was agitated with the stirrer for about 30 minutes, and then a sample taken from the lower drain of the compounding tank and the pH checked. After this. the solution was drained from the compounding tank and passed through two membrane filters, each having a 0.22 micron porosity. The membrane filters were in series. At the beginning of the filtration, the nitrogen pressure was increased to 30 psig on the solution to test the integrity of the filters and thereafter the filtration proceeded under one atmosphere pressure. The filtrate was collected in a reservoir and blanketed with the above-described carbon dioxide-nitrogen blanket. The reservoir was connected to a bottling apparatus which dispensed 500 milliliters (plus a 2 percent overfill) to each of the infusion bottles. Prior to the time that the bottles had received the therapeutic composition, they had been preflushed by passing a steady stream of the above-described (O -N mixture therein. After each of the bottles had received the 500 milliliters of therapeutic composition, the solution within each of the bottles was again blanketed with the abovedescribed Co -N mixture and then immediately sealed. Each bottle is inspected for particulate matter by passing it through an illuminated path in front of a black and white back' ground. In addition, sample bottles from the filling op eration were removed from the filling operation at regular intervals and subjected to standard quality control and toxicity testing. The material was found to be sterile.

EXAMPLE 2 TABLE V TYPICAI. UNIT IN COMPONENT GRAMS PER 500 Ml Sodium Chloride 3.244 Sodium Bicarbonate (1.672 Potassium Chloride (L503 Magnesium Sulfate Heptahydrate (1.554

TABLE VI TYPICAL UNIT lN COMPONENT GRAMS PER 500 Ml Sodium Chloride 3.360 Sodium Bicarbonate 0.840 Potassium Chloride 0.54] Magnesium Sulfate Heptahydrate 0.678

Furthermore. a typical 500 ml unit of a solution having an osmolality of 200 has the formulation set forth in Table VII below:

TABLE Vll TYPICAL UNIT lN COMPONENT GRAMS PER 500 Ml Sodium Chloride 0.245 Sodium Bicarbonate 0.5 I4 Potassium Chloride 0.355 Magnesium Sulfate Heptahydratc (H lit The solutions set forth in Tables V-Vll can be maintained at any suitable pH from 6-8.5 by maintaining the proper ratio of CO: to inert gas in the protective blanket used over the solution during the blanketing steps as set forth in the procedure in Example 1.

it is noted that in all of the formulations set forth in Tables V-Vll. 0.05 percent W/V disodium edetate can be added if desired.

While this invention has been described in relation to its preferred embodiments. it is to be understood that various modifications thereof will now be apparent to one skilled in the art upon readingthis specification and it is intended to cover such modifications as fall within the scope of the appended claims.

I claim:

1. A method of making an injectable aqueous solution comprising:

a. dissolving in a sterile water volume from about 75 to about 150 millimoles per liter of sodium cation. about 5 to about 50 millimoles per liter of potassium cation. about 5 to about 50 millimoles per liter of bicarbonate ion. and about 75 to about l5O millimoles per liter of chloride ion to form a solution having an osmolality in the range from about 170 to about 460 and a pH in the range of from about 6-8.5;

b. blanketing the resulting solution with a mixture of carbon dioxide and another inert gas. the carbon dioxide being present in said gaseous mixture in an amount to provide a partial pressure on said liquid which is substantially equal to the partial pressure of carbon dioxide which is produced from equilibrium with the bicarbonate ions in said solution to thereby stabilize said solution: and

c. dispensing said solution into at least one sterile container. and while said dispensed solution is still blanketed by said gas mixture. hermetically sealing said container containing said solution and said gas mixture blanketed thereover.

2. The method of claim I wherein said solution is maintained at a temperature in the range of from about 25 to about 50C during said blanketing.

3. The method of claim 2 wherein said blanket is maintained at about l atmosphere pressure and the partial pressure of said carbon dioxide within said blanket is maintained in a range of from 0.0007 to 0.92 atmospheres.

4. The method of claim 3 wherein said inert gas is nitrogen.

5. The method of claim 1 further comprising steriliz ing the resultant stabilized solution.

6. The method of claim 5 wherein said sterilizing comprises filtering said resultant stabilized solution while under said blanket to remove contaminants therefrom.

7. The method of claim 6 wherein said filtering com prises passing said solution through a membrane filter having pore sizes of less than 1 micron.

8. The method of claim 7 wherein said filter has pore sizes of 0.22 microns.

9. The method of claim 7 wherein said solution is passed through two of said filters in series.

10. The method of claim I wherein said sterile container is preflushed with gas having the same composi tion of the said gaseous mixture prior to dispensing said solution therein.

11. A method of making an injectable aqueous solution comprising:

a. adding to a sterile water volume. water soluble salts containing from about to about l50 millimoles per liter of sodium cation. about 5 to about 50 millimoles per liter of potassium cation. about 5 to about 50 millimoles per liter of bicarbonate ion. and about 75 to about millimoles per liter of chloride ion sufficient to form an aqueous solution having an osmolality in the range from about I70 to about 460 and a pH in the range of from about 6.0 to 8.5;

b. blanketing the resulting mixture with a mixture of carbon dioxide and another inert gas. the carbon dioxide being present in said gaseous mixture in an amount to provide a partial pressure on said liquid which is substantially equal to the partial pressure of carbon dioxide which is produced with water from equilibrium with said bicarbonate ion in said solution to thereby stabilize said solution;

c. agitating the resulting mixture while under said blanket to cause said salts to thoroughly dissolve in said sterile water and form said solution; and

d. dispensing said solution into at least one sterile container, and while said dispensed solution is still blanketed by said gas mixture. hermetically sealing said container containing said solution and said gas mixture blanketed thereover.

12. The method of claim 11 wherein said mixture is maintained at a temperature in the range from about 25 to about 50C during said blanketing.

13. The method of claim 12 wherein said blanket is maintained at about I atmosphere pressure and the partial pressure ofsaid carbon dioxide within said blanket is maintained in a range of from 0.0007 to 0.92 at mospheres.

14. The method of claim 13 wherein said inert gas is 

1. A METHOD OF MAKING AN INJECTABLE AQUEOUS SOLUTION COMPRISING: A. DISSOLVING IN A STERILE WATER VOLUME FROM ABOUT 75 TO ABOUT 150 MILLIMOLES PER LITER OF SODIUM CATION, ABOUT 5 TO ABOUT 50 MILLIMOLES PER LITER OF POTASSIUM CATION, ABOUT 5 TO ABOUT 50 MILLIMOLES PER LITER OF BICARBONATE ION, AND ABOUT 75 TO ABOUT 150 MILLIMOLES PER LITER OF CHLORIDE ION TO FORM A SOLUTION HAVING AN OSMOLALITY IN THE RANGE FROM ABOUT 170 TO ABOUT 460 AND A PH IN THE RANGE OF FROM ABOUT 6-8.5; B. BLANKETING THE RESULTING SOLUTION WITH A MIXTURE OF CARBON DIOXIDE AND ANOTHER INERT GAS, THE CARBON DIOXIDE BEING PRESENT IN SAID GASEOUS MIXTURE IN AN AMOUNT TO PROVIDE A PARTIAL PRESSURE ON SAID LIQUID WHICH IS SUBSTANTIALLY EQUAL TO THE PARTIAL PRESSURE OF CARBON DIOXIDE WHICH IS PRODUCED FROM EQUILIBRIUM WITH THE BICARBONATE IONS IN SAID SOLUTION TO THEREBY STABLIZE SAID SOLUTION; AND C. DISPENSING SAID SOLUTION INTO AT LEAST ONE STERILE CONTAINER, AND WHILE SAID DISPENSED SOLUTION IS STILL BLANKETED BY SAID GAS MIXTURE, HHORMETICALLY SEALING SAID CONTAINER CONTAINING SAID SOLUTION AND SAID GAS MIXTURE BLANKETED THEREOVER.
 1. A method of making an injectable aqueous solution comprising: a. dissolving in a sterile water volume from about 75 to about 150 millimoles per liter of sodium cation, about 5 to about 50 millimoles per liter of potassium cation, about 5 to about 50 millimoles per liter of bicarbonate ion, and about 75 to about 150 millimoles per liter of chloride ion to form a solution having an osmolality in the range from about 170 to about 460 and a pH in the range of from about 6-8.5; b. blanketing the resulting solution with a mixture of carbon dioxide and another inert gas, the carbon dioxide being present in said gaseous mixture in an amount to provide a partial pressure on said liquid which is substantially equal to the partial pressure of carbon dioxide which is produced from equilibrium with the bicarbonate ions in said solution to thereby stabilize said solution; and c. dispensing said solution into at least one sterile container, and while said dispensed solution is still blanketed by said gas mixture, hermetically sealing said container containing said solution and said gas mixture blanketed thereover.
 2. The method of claim 1 wherein said solution is maintained at a temperature in the range of from about 25* to about 50*C during said blanketing.
 3. The method of claim 2 wherein said blanket is maintained at about 1 atmosphere pressure and the partial pressure of said carbon dioxide within said blanket is maintained in a range of from 0.0007 to 0.92 atmospheres.
 4. The method of claim 3 wherein said inert gas is nitrogen.
 5. The method of claim 1 further comprising sterilizing the resultant stabilized solution.
 6. The method of claim 5 wherein said sterilizing comprises filtering said resultant stabilized solution while under said blanket to remove contaminants therefrom.
 7. The method of claim 6 wherein said filtering comprises passing said solution through a membrane filter having pore sizes of less than 1 micron.
 8. The method of claim 7 wherein said filter has pore sizes of 0.22 microns.
 9. The method of claim 7 wherein said solution is passed through two of said filters in series.
 10. The method of claim 1 wherein said sterile container is preflushed with gas having the same composition of the said gaseous mixture prior to dispensing said solution therein.
 11. A method of making an injectable aqueous solution comprising: a. adding to a sterile water volume, water soluble salts containing from about 75 to about 150 millimoles per liter of sodium cation, about 5 to about 50 millimoles per liter of potassium cation, about 5 to about 50 millimoles per liter of bicarbonate ion, and about 75 to about 150 millimoles per liter of chloride ion sufficient to form an aqueous solution having an osmolality in the range from about 170 to about 460 and a pH in the range of from about 6.0 to 8.5; b. blanketing the resulting mixture with a mixture of carbon dioxide and another inert gas, the carbon dioxide being present in said gaseous mixture in an amount to provide a partial pressure on said liquid which is substantially equal to the partial pressure of carbon dioxide which is produced with water from equilibrium with said bicarbonate ion in said solution to thereby stabilize said solution; c. agitating the resulting mixture while under said blanket to cause said salts to thoroughly dissolve in said sterile water and form said solution; and d. dispensing saiD solution into at least one sterile container, and while said dispensed solution is still blanketed by said gas mixture, hermetically sealing said container containing said solution and said gas mixture blanketed thereover.
 12. The method of claim 11 wherein said mixture is maintained at a temperature in the range from about 25* to about 50*C during said blanketing.
 13. The method of claim 12 wherein said blanket is maintained at about 1 atmosphere pressure and the partial pressure of said carbon dioxide within said blanket is maintained in a range of from 0.0007 to 0.92 atmospheres. 